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Harness the Power of the Sun

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In the past, when I thought of solar power I would automatically think solar panels or more specifically, solar photovoltaics. However, within the last couple of months I've gained a better understanding of the variety of ways we can harness the sun's abundant energy to help meet our power needs.

Step outside on a hot and sunny summer day, and you'll feel the power of solar heat and light. There are many ways to take advantage of this natural resource. One option I find particularly interesting is passive solar design.

Your home's windows, walls, and floors can be designed to collect, store, and distribute solar energy in the form of heat in the winter, and reject solar heat in the summer. Passive solar design can be applicable to all climates.

There are several elements to passive solar design. The south side of a building almost always receives the most sunlight. Therefore, homes designed for passive solar heating usually have large, south-facing windows.

Materials that absorb and store the sun's heat can be built into the sunlit floors and walls. The floors and walls will then heat up during the day and slowly release heat at night, when the heat is needed most. This passive solar design feature is called direct gain.

Other passive solar heating design features include sunspaces and trombe walls. A sunspace—much like a greenhouse—is built on the south side of a building. As sunlight passes through glass or other glazing, it warms the sunspace. Proper ventilation allows the heat to circulate into the home.

A trombe wall is a very thick, south-facing wall that is painted black and made of a material that absorbs heat. A pane of glass or plastic glazing, installed a few inches in front of the wall, helps hold in the heat. The wall heats up slowly during the day; then as it cools gradually during the night, it gives off its heat inside the building.

Many passive solar heating design features also provide daylighting. Daylighting is simply the use of natural sunlight to brighten up a building's interior.

Too much heat absorption can be a problem during the hot summer months. Fortunately, there are many design features that help keep passive solar buildings cool in the summer. For example, overhangs can be designed to shade windows when the sun is high in the summer. Sunspaces can be closed off from the rest of the building; and a building can be designed to use fresh-air ventilation in the summer.